Power hammer



Aug. 22, E950 F. H. KIND w 2,519,477

POWER HAMMER Filed April 25, 1947 v 23 22 9 a 2a 21 7 F/ G. 6`.

fd IN VEN TOR.

vL/memce. ,LA /ma BY l @vara/G24 Arron/vans Patented Aug. 22, 1950 POWER HAMMER Frederick H. Kind, Racine, Wis., assignor toRacine Tool & Machine Company, Racine, Wis.,

a corporation f Wisconsin- Application April 25, 1947, Serial No. 743,750

The invention relates to percussion tools, and more particularly to a reciprocatory or power hammer.

One object of the invention is to improve upon reciprocatory hammers of the spring driven type by providing a double spring connection between the rotary driven shaft and the hammer associated with means for limiting the whip oi the springs and thus greatly prolonging the useful life of the tool. It has been found in practice that where a single freely whippable spring is provided as a drive connection for the hammer, that frequent breakage of the spring occurs and that such a tool is commercially impracticable.

A further object of the invention is to provide a reciprocatory hammer in which the hammer is operated by the stored up energy of a spring means which is released after a predetermined pressure or force has been built up in said spring means, the power for operating the spring preferably being a rotary motor driven drive shaft.

A further object of the invention is to provide a hammer including a reciprocatory piston, a rotary drive shaft, a connecting rod between said shaft and piston including a spring, and spring pressed detents engageable with said piston and releasable when their holding force is overcome by the greater pressure of the driving spring, thus causing a quick release of the energy stored up in the spring.

A further object of the invention is to provide a cushioning means for the tool carrying socket member.

A further object of the invention is to provide a simple and effective form of tool guide and tool retainer member.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a vertical sectional view through a hammer embodying the invention;

Figs. 2, 3, and 4 are diagrammatic sectional views with parts broken away showing the different positions of the parts, the drive means being shown in end elevation;

Fig. 5 is a detailed horizontal sectional view taken on the line 5 5 of Fig. 1.

Fig. 6 is a detailed sectional view taken on the line 6 6 of Fig. 1.

Referring to Fig. 1, the numeral 6 designates a motor or prime mover which may be either an electric motor, as shown, or a small portable internal combustion engine whose drive shaft I is journalled in a frame 8 and carries a gear S mesh- 4 Claims. (Cl. 125-31) ing with a gear I on a crank shaft I I, said frame being suitably split to permit the mounting of said shafts therein, the gears 9 and Ill forming a speed reduction drive between the main drive and the hammer drive shaft II.

A cylinder I2 is formed integral with 01 suitably connected to the frame 8 and has a bore I3 in which a reciprocatory piston or hammer member I4 is mounted. The piston I4 is preferably formed in two parts, a guide barrel or sleeve I5 and a hardened metal head I6 having a shank I'i of reduced diameter projecting up into said sleeve and provided with double or parallel thread or spring mounting grooves I8.

The crank shaft has a spring mounting and spring side whip restraining member I9 secured thereto by a split bearing or removable cap type of connection 20, the end of said member adjacent said crank shaft having double or parallel disposed spring receiving grooves 2i and a carrying diametrically disposed spring locking pin 22.

A double spring 23, that is two springs in which the coils of one spring are threaded or disposed between the coils of the other spring similar to a double screw thread have their ends lrespectively connected to the head I6 and the member I9 by being threaded or-turned onto the grooves I8 and 2| of said members. At the head, the ends 24 of these springs abut the diametrically disposed ends of said grooves I8 and need no other means to hold them tight since the natural tendency of these springs is to wind toward said ends, but at their upper ends vsaid spring ends are rel tained against movement relative to the member I9 by the pin 22 engaging a notch 25 in said spring, it being noted that the ends of said springs of this double spring structure are one hundred eighty degrees apart. It is also to be noted that the member I9 extends down in spaced relation or free of the springs 23 more than half and preferably about three-quarters of the free length of said springs between their anchorage points and is tapered at its lower end 26.

A tool 21, such as a vrailroad ballast tamping tool, is slidably mounted in a pair of guides 28 and 29 disposed at the lower end of the cylinder IZ.

The guide 28 is in the form of a sleeve 30 slidably mounted in the bore 3l of a casing member 32 and having a flanged head 33 resting( upon an annular rubber cushion 34 slidably mounted in the enlarged bore 35 in the lower end of the cylinder I2 and retained therein by the member 32 which is secured to the cylinder by bolts 36. The cushion 34 takes the shock of the blow delivered by the hammer or piston I4 when said hammer has forced the upper end of the tool 21 to a level with the upper end of the sleeve or guide 30 and also acts to return the tool toward the piston though it will be understood that since in tools of this kind the operator may put pressure on the tool by forcing it into the material being actedupon;thisrpressure'togetherewith the weight .of the/'device will also'iserve to shiftth'e tool 21 upwardly relative to the cylinder to receive another blow from the hammer.

The guide 29 is formed of two complementary half sleeve sections 31 having a polygonalgusually hexagonal, bore 38 toiconform Eto the .cross section of the shank of the tool which .sect/ions are detachably secured in operative position by set screws 39 whose reduced .ends-.engage in holes 40 in the sections 37. In use the sholder or flange 4i on the tool works between the guides 2B and 29 and preventsthe tool from falling out of the device,` but .theutool can-bereadily removed by loosening the 'fsetfscrews ifrom the 1 sections f31, so thatt-they can be 'removed from .the lower fend ofthefdevice :to permitthetool-fto dropout.

With the above Lconstruction, the continuous rotary motion1of -lthefshait -.H @acts to reciprocate the spring 23 pand 'to ;compress..-said spring .between :their `anchored ends Aon the down stroke of-fsaid crank shaft andfallowthemto' expand on its -up Ystroke, -thus :imparting energy to the vsprings .-23 which 2in .turn imparts their energy to Lthe hammer "i4 :causing Lits trapid :reciprocationfand'that -fa certain amountaof Vwhipping action 'imparted to "the :springs beca-use of ytheir angular movement '-.is :desirable :as ait -increases thezoverall energy-,deliveredby the springs .23 to thefahammer .though tool muchwhipping action y is impractical and .-i-t results in requent Aspring breakage, :so that while the :member :l 9 '-permits ,some side :whipxof the spring, rit limi-ts .it `to an extent which @greatly reduces liability of spring breakage :under this action.

The :above -construction provides a Tsimple and emcient `form :of `spring -hammer -in 'whch the rapid-reciprocation of thefspring and ipiston Vproduces i hammer blows-on -the' tool, but .lin :some instances it `may be fdesirable v-to temporarily hold `the hammer i4-as theienergyiis -being stored up inthe :springs 23, and for ithis ipurpose'the =piston -H lis `provided with :an #annular AAV.-f:.froove '42 to receive @the pointed ends -Yli3 'of l'one vor more diametrically i disposed idetents A4l! `slidably 'mounted in bores .45 Vin 'the cylinder 42 `and yieldingly pressed 'inwardly 'by rthe "freerends .of yilatsprings I6 Ywhich :are fanchored aat :their other lends to the -cylinder "byscrewsdf'i, .lhe tension ofthe springs -46 1isy such as :to resist-.outward movement Io1 the detents i4 `until v:substantially the -maximum energy fhas vbeen built iup in the-springs Y2% whereupon th'e detents M 1are released `or `moved outwardly by *the wedging action iof the groove 42 thereon. and the fhammer descends 'with a quick movement f'from Ithepositionshown in Fig. 'B to -fthe position -rshown lin Fig. 4 :hitting Athe top nl' the vsha'nk'of 'the .tool 21 #a sharp blow, LFig .2 showing gthe positionaofthe :parts .when :the "hame mer is in its upper position, Fig. 3 their position Just before -the release-of :theaietentsmn counter y'clockwise rotationaof theeshaft iii, and -Figf4the iinish of 'the :hammer fstroke. :For the sake of simplicity -only la, single vspring :has been lshown .in Avliligs. .2 :to -4 :as 'connecting the *crank -shait I-l with .the fhammerrbutits '.toibe understood that the double spring 23 and the member I9 would be used in practice.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claims.

What I claim as my invention is:

1. TIn 'adevfioe-ol? the .'clia'raeter descrhed, the Vvcombination off-a rotary drive shaft, areciprocatory hammer, a drive connection between said eshaft and hammer including a compression vspringend releasable detente normally engageable with said hammer to arrest its movement untilneleasedvby aninorease of tension in said spring, said/hammer adapted to have impact en- 'f-gageinent withV a tool.

2..In adev-ice of the character described, the combination with a rotating drive shaft, a cylinder,1ahammer working in said cylinder, a connecting rod having an eccentric drive connection withsaid shaft andinelu'ding z an fenergy transmitting spring .operatively Leon'ecting :said shaft with said piston, and spring pressed detentsinormally Aengageable with the :hammer to .arrest lits movement until released 'by fthe increased tension 'iof .said energy =itransmitting spring, said hammer adapted to :have :impact .engagement with a'tool mounted :in the lower end of 1said cylinder.

In apowe'rtool, 'the :combination .of fa rotary idrivei'shaft having fa crank, .a recipro'catory hammer, a double :spring .anchored at one end to said fhammer an'd in which 'the 'c'oils .'of 'fthe springs :forming 'the l:double 'spring have threaded Irela'tion with each other, `and a "spring whip 'limiting member connecting the upp'erf'entl of said lSdouble spring' with lsaid f crank for oscillatory and freciproca'tory movement '.thereby, and terminating short of the anchorage `connection o'f 'said spring vwith Vsaid 'hammer't'o fallow va ilimlited amount 'o'f free whipof said doublefsp'rin'g without I'danger of spring breakage 4. In -a power tool, the combination I`of farotary fcrank vfshaft, 'a lcylinder, `a lpiston 'hammer working fin said cylinder, -fa -fspring whip vlimiting member'having one end journalledonthe crank of said 'crank shaft and having 1 its 'otheruend free tofoscillate, anda doblefspring'ranchored atlone endlto 'said hammer and .connected at :its 'other end to the journalled end of said whip 'limiting member-'and in whichth'e coils "formingfth'e-dou- 'ble fspring have threaded relation with each other, said whip limiting member extending into the 'convolutions of said'double spring rinispaced relation thereto and allowing a 4limited .amount of free whip of said spring.

'FREDERICK H. KIND.

REFERENCES CITED The `following references areo'f record in the le of this patent:

UNITED STATES PATENTS Number Name 'Date 1,774,905 Smrdel lSept. 2, 1930 '1,968,055 Phillips '.Ju'ly y31, AIV1934 2,241,184 Clark 'May '6, 1941 FOREIGN 'PATENTS Number Country I'Dete 19,329 Great Britain .'Apr. .15, 191,1 :860,325 France. Sept. 24, v11940 

